In the design of optical transceivers for wireless local area network (LAN) applications, there is a need to make the system as non-directional as possible while minimizing cost, complexity, and transmitted optical power. The system designer is challenged with devising a scheme to maximize the collection and concentration of the transmitted optical energy without significantly reducing the field of view of the transceiver. The optics required to convert the modulated optical signal may represent a significant portion of the direct material cost of the transceiver.
An optimal method to collect and concentrate the optical signal is the compound parabolic concentrator (CPC), described in High Collection Nonimaging Optics by W. T. Welford and R. Winston, Academic Press .COPYRGT.1989. The CPC may be formed from a cavity with reflective interior walls, or from a solid, transparent dielectric material employing total internal reflection. Solid CPCs provide an enhancement in concentration which is proportional to the square of the index of refraction of the material from which they are formed.
An example of a photodiode alignment structure known in the prior art is the MFOD71 fiber optics photodetector described in Optoelectronics Device Data, Motorola, Inc. .COPYRGT.1989. This device is designed to retain and align a photodiode with a 1000 micron core plastic fiber, but it does not provide orientation for a plurality of devices or address the need for an optical bond.
Accordingly, there exists a need for a cost-effective method and device to provide alignment for a plurality of photodiodes and associated CPCs, and to provide a fixture for retaining a solid CPC during the process of optically bonding the exit aperture to a photodiode.